Dome-loaded pressure regulators

ABSTRACT

Dome-loaded pressure regulators are disclosed. An example pressure regulator includes body having a pressure inlet and a pressure outlet. A piston is disposed in the body and fluidly coupled to the pressure inlet, the pressure outlet, and the pressure control inlet. The piston is configured to contact a valve seat and to control the flow of fluid from the pressure inlet to the pressure outlet in response to a pressure applied to a surface of the piston via the pressure control inlet.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to pressure regulators and,more particularly, to dome-loaded pressure regulators.

BACKGROUND

Many process control systems use pressure regulators to control thepressure of a process fluid, to control a pressure applied to a processcontrol device (e.g., an actuator), etc. Pressure reducing regulatorsare commonly used to receive a relatively high pressure fluid source andoutput a relatively lower regulated output fluid pressure. In thismanner, despite the pressure drop across the regulator, a pressurereducing regulator can provide a relatively constant output fluidpressure for a wide range of output loads (i.e., flow requirements,capacity, etc.).

Some pressure reducing regulators commonly referred to as dome-loadedpressure reducing regulators utilize a dome or pilot stage that receivesa control pressure (e.g., a setpoint pressure or desired outputpressure). The control pressure in the dome or pilot stage typicallydrives a sensor (e.g., a piston) which, in turn, drives a valve stem andits plug against a bias spring toward or away from a valve seat so thatthe output pressure of the regulator substantially equals the controlpressure.

However, such dome-loaded regulator designs typically use a separatepiston or sensor and valve plug/stem assembly. Due to the separatepiston and valve plug/stem assemblies, these types of regulators areprone to overshooting/undershooting a target output pressure and/or mayproduce an oscillating output pressure. In particular, because thepiston is not mechanically joined to the valve stem, the piston canseparate from the valve stem/plug assembly resulting in a transitory ormomentary loss of control over the position of the plug relative to theseat. As a result, these types of pressure reducing regulator designsmay produce unstable (overshooting, undershooting, oscillating, etc.)output pressures in response to rapid changes in the dome pressure(i.e., the control pressure). For example, in some known applications,control pressure or dome pressure is supplied or controlled via fastacting solenoid valves, which produce rapid pressure changes in the domeand, thus, aggravate the above-described stability problem associatedwith these known dome-loaded regulators. In addition to the stabilityissues associated with known dome-loaded pressure reducing regulatordesigns, the above-described dome-loaded pressure reducing regulatorsutilize a relatively large number of parts, which tends to increase thematerial and maintenance cost of the regulators as well as thelikelihood of regulator failure.

A pressure reducing regulator having relatively few moving parts and asubstantially unitary piston or sensor and valve plug assembly isdescribed in U.S. Patent Publication No. 2004/0007269, the entiredisclosure of which is incorporated herein by reference. The pressurereducing regulator described in this patent application publication isan in-line pressure reducing regulator that does not utilize a pilotstage or dome to control output pressure and, instead, uses springs toestablish a predetermined output pressure. In addition to reducing thenumber of moving parts, the substantially unitary piston or sensor andvalve plug assembly also eliminates the possibility of the valve plugfrom separating from the piston/sensor, as can occur with thedome-loaded regulator designs noted above.

Still further, in some applications it is desirable to provide multiplepressure outputs (which may be different pressure values) derived from asingle source pressure. Commonly, such multiple output pressureapplications are implemented by fluidly coupling two or more pressurereducing regulator assemblies, such as the dome-loaded regulatorsdescribed above, via a manifold and/or tubing. However, such multipleoutput regulator assemblies are typically expensive to assemble, bulky,heavy, difficult to maintain, etc.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is cross-sectional view of a known dome-loaded pressure reducingregulator.

FIG. 2 is a cross-sectional view of an example dual output dome-loadedpressure reducing regulator.

SUMMARY

In one disclosed example, a pressure regulator includes a body having apressure inlet and a pressure outlet. A piston is disposed in the bodyand fluidly coupled to the pressure inlet, the pressure outlet, and thepressure control inlet. The piston is configured to contact a valve seatand to control the flow of fluid from the pressure inlet to the pressureoutlet in response to a pressure applied to a surface of the piston viathe pressure control inlet.

In another disclosed example, a pressure regulator includes adome-loaded pressure regulating valve fluidly coupled to a pressureinlet, a pressure outlet, and a control pressure. The pressureregulating valve includes a piston configured to engage a valve seat andto respond to the control pressure to control the flow of fluid betweenthe pressure inlet and the pressure outlet via the valve seat.

In still another disclosed example, a pressure regulator includes a bodyhaving a pressure inlet and first and second pressure outlets. Theexample regulator also includes first and second pressure regulatingvalves disposed in the body and fluidly coupled to the pressure inletand the respective first and second pressure outlets. Each of the firstand second pressure regulating valves includes a piston having a firstportion to receive a control pressure and a second portion fixed to thefirst portion and configured to sealingly engage a valve seat.

DETAILED DESCRIPTION

In general, the example multiple output dome-loaded pressure reducingregulator described herein provides one regulator body that holdsmultiple pressure regulating valves. Each of the pressure regulatingvalves provides an independent pressure output or outlet and theindependent pressure outputs are derived from a single pressure sourceinlet of the regulator body.

Additionally, in contrast to some known dome-loaded pressure regulatingvalves, the example multiple output pressure reducing regulatordescribed herein utilize pressure regulating valves having asubstantially unitary or integrated piston or sensor and valve assemblythat substantially reduces or eliminates output pressure instabilities(e.g., overshooting, undershooting, oscillation, etc.) such as thosethat may result from rapid changes in dome or control pressure. Theintegrated piston or sensor and valve assembly also serves to reduce thenumber of parts needed to implement the pressure regulating valves incomparison to some known pressure regulating valves, thereby enabling amore compact design, improved reliability, and lower costs.

Thus, the example integrated multiple output regulator configurationdescribed herein provides a multiple output regulator assembly having asingle regulator body that eliminates the need for numerous fittings,tubing, bulky and expensive manifolds, etc., as was required for someknown multiple output regulator designs. Further, the pressureregulating valves used to implement the example multiple outputregulator have fewer internal components. As a result, the examplemultiple output regulator assembly described herein may provide lowermanufacturing/fabrication costs in addition to lower maintenance costsdue to the improved reliability that results from having fewer overallcomponents.

Before discussing the example multiple output pressure reducingregulator of FIG. 2, a known dome-loaded pressure reducing regulator 100is first described in connection with FIG. 1. The known pressurereducing regulator 100 of FIG. 1 includes a body 102 having an inlet104, an outlet 106, and a pilot or control pressure input 108. A plug orbonnet 110 is threaded into the body 102 to form a chamber or dome space112. An o-ring 114 forming a seal against an inner passage 116 of thebody 102 is backed by a ring 118 to prevent extrusion of the o-ring 114between the bonnet 110 and the body 102. A piston or sensor 120 isslidably engaged with the passage 116 and includes an o-ring 122 andbacking rings 124 and 126 to form a seal against the passage 116. Thepiston 120 contacts a valve assembly 128 via a shaft 130 of a plug 132.The plug 132 is urged or biased toward or against a seat 134 via aspring 135.

In operation, a desired control pressure is applied to the pilot input108 and, thus, to the piston 120. If the pressure at the outlet 106 isless than the control pressure, the piston 120 is displaced toward thevalve seat 134 to drive the plug 132 away from the seat 134. As aresult, the restriction between the inlet 104 and the outlet 106decreases to enable the pressure at the outlet 106 to increase. As thepressure at the outlet 106 increases, the amount of pressure urging thepiston 120 away from the valve seat 134 increases. When the pressureapplied to a first face 136 of the piston 120 (i.e., the pressure at thepilot inlet 108) is substantially equal to the pressure applied to asecond face 138 of the piston 120 (i.e., the pressure at the outlet106), the piston 120 will remain relatively stationary within thepassage 116 and the pressure at the outlet 106 will remain substantiallyconstant and equal to the pressure at the pilot input 108.

However, the known dome-loaded pressure reducing regulator 100 of FIG. 1is susceptible to output pressure instability. For example, in someapplications, the dome pressure supply (i.e., the pressure applied atthe pilot input 108) to the regulator 100 is controlled using twosolenoid valves (neither of which are shown). One solenoid valve opensto introduce air pressure into the dome space 112 via the pilot input108 and the other solenoid valve bleeds pressure out of the dome space112 via the pilot input 108. While such a solenoid configurationprovides a fast acting method of introducing high-pressure air into theregulator dome space 112, the configuration is relatively susceptible toinstability (e.g., overshooting, undershooting, oscillations, etc.).More specifically, the rapid introduction of air (e.g., the introductionof a quick burst of air) into the dome space 112 may cause the regulator100 to open quickly to a maximum flow condition, which then causes theoutput pressure of the regulator 100 to overshoot. In response to theoutput pressure overshoot, the valve assembly 128 in the regulator 100closes rapidly, which causes the regulator output pressure to undershootthe desired control pressure. Thus, this instability can result in asuccession of pressure overshoots and undershoots or continuousoscillation of the regulator output pressure.

FIG. 2 is a cross-sectional view of an example dual output dome-loadedpressure reducing regulator 200. The example dual output dome-loadedpressure reducing regulator 200 includes first and second pressurereducing regulators 202 and 204 having respective pressure reducingvalve assemblies 206 and 208. As shown in FIG. 2, the regulators 202 and204 are disposed within a single substantially unitary body 210, whichmay be made of metal such as, for example, brass, stainless steel, orany other metal or material suitable for the intended application of thepressure reducing regulator 200. The body 210 includes a single pressureinlet 212, which provides a pressure source to the regulators 202 and204 and independent multiple or dual pressure outlets or outputs 214 and216, corresponding to the respective first and second regulators 202 and204.

Turning in detail to the first regulator 202, a bonnet or cap 218 isthreadingly and sealingly engaged with the body 210. The bonnet 218provides a pilot or pressure control inlet or input 220, which forms afluid passage 222 to a chamber or dome space 224. As depicted in theexample of FIG. 2, a fluid restrictor 226 may be interposed in the fluidpath between the pressure control inlet 220 and the chamber 224.

A sensor or piston 228 slidably engaged with the body 210 is fluidlycoupled to the pressure inlet 212, the pressure outlet 214 and thepressure control input 220 via the chamber 224 and the passage 222. Thepiston 228 has a first portion 230 having a surface 232 that receives apressure (i.e., the pressure in the chamber or dome space 224) via thepressure control input 220. Additionally, the piston 228 has a secondportion 234 configured to contact a valve seat 236 and to control theflow of fluid from the pressure inlet 212 to the pressure outlet 214 inresponse to the pressure applied to the surface 232 of the piston 228via the pressure control input 220. In contrast to some knowndome-loaded pressure reducing regulators and regulating valves, thefirst and second portions 230 and 234 of the piston or sensor 228 arefixed together (i.e., cannot separate during operation of the valve 206)and, thus, form a substantially one-piece or unitary member.

The valve seat 236 may be a plug-shaped member made substantially of aplastic material, or any other material that is relatively softer thanthe material composing the piston 228. A spring 238 disposed between aseat portion 240 of the body 210 and a shoulder 242 of the piston 228biases an annular surface 244 of a central bore 245 of the piston 228toward or into sealing engagement or contact with the valve seat 236. Aplurality of circumferential seals (e.g., o-rings) 246, 248, and 250disposed in respective annular channels or grooves 252, 254, and 256sealingly engage the body 210 and the bonnet 218. The seal 250 furtherincludes a backing ring 258 to inhibit or prevent extrusion of the seal250 from its groove 256.

In operation, a control pressure (e.g., a desired output pressure) isapplied to the pilot or pressure control input 220. The control pressurethen pressurizes the dome space or chamber 224 via the fluid restrictor226. In this manner, the fluid restrictor 226 prevents an overly rapidincrease (or decrease) of the pressure applied to the surface 232 of thepiston 228 and, thus, tends to substantially reduce or eliminatepressure instabilities (e.g., overshooting, undershooting, oscillation,etc.) at the outlet 214. For example, when solenoid valves (not shown)are used to increase (i.e., load) or decrease the pressure in the domespace 224, the fluid restrictor 226 slows the flow of air to/from thedome space 224 to the solenoid valves, which slows the movement of thepiston 228 to prevent the piston 228 and, thus, the pressure at theoutlet 214 from oscillating or cycling about a desired output pressure.

During operation, the control pressure applied to the piston surface 232via the inlet 220 urges the piston 228 against the force of the spring238 to move the annular surface 244 away from the seat 236, whichdecreases the restriction between the inlet 212 and the outlet 214 toenable the pressure at the outlet 214 to increase. As the pressure atthe outlet 214 increases, the pressure against the shoulder 242 andsurface 260 of the piston urges the piston 228 against the pressure inthe dome or chamber 224 to move the annular surface 244 toward the seat236, which increases the restriction between the inlet 212 and theoutlet 214 to enable the pressure at the outlet 214 to decrease (or tostop increasing). When the pressures urging the annular surface 244 awayfrom the seat 236 and toward the seat 236 are in balance, the pressureat the outlet 214 is substantially equal to the pressure provided viathe pressure control inlet 220 to the dome or chamber 224.

In addition to sealing the piston 228 to the body 210, the seals 246,248, and 250 also serve to increase the output stability of theregulator 202. More specifically, the seals 246, 248, and 250 provide africtional engagement with the body 210 that dampens the movements ofthe piston 228 in response to relatively rapid pressure changes orperturbations at the inlet 212, the pressure control input 220, and/orthe outlet 214.

The substantially one-piece or unitary piston 228 further enhancesstable operation of the regulator 202. In particular, unlike some knowndome-loaded pressure regulators, the plug or sealing surface (e.g., theannular surface 244) is integral with the piston or sensor 228, therebyeliminating any possibility of separation between the mechanismcontrolling the flow of fluid past the seat 236 and the mechanism thatsenses or which is exposed to and which is responsive to the pressure inthe dome space 224.

The bias provided by the spring 238 causes the annular surface 244 tosealingly contact or engage the seat 236 in the absence of a controlpressure in the dome space 224 (e.g., zero pounds per square inchgauge). In this manner the regulator valve 206 is configured as anormally-closed device. Additionally, the regulator valve 206 provides apositive (e.g., self-healing) seal design. For example, if the seat 236develops a leak from debris or any imperfection associated with theannular surface 244 and/or the seat 236, the pressure at outlet 214 willincrease and apply a greater force on the shoulder 242 and the surface260 of the piston 228 to drive the annular surface 244 against the seat236. In the case where the seat 236 is made of a relatively softermaterial (i.e., softer than the surface 244 of the piston 228) such as,for example, plastic, the seat is deformed and/or conforms toaccommodate the imperfection, debris, etc. to seal against the surface244. Once deformed or conformed to the surface 244, the leakage past theseat 236 is substantially reduced or eliminated.

The second pressure reducing regulator 204 and valve 208 is formed usingthe same components as those used for the first regulator 202 and, thus,the second regulator 204 and its valve 208 are not described in greaterdetail herein. Additionally, although not shown, safety or relief valvesmay be added to the outlets 214 and 216 of the regulators 202 and 204,and an inlet filter may be placed in the inlet 212 to prevent debrisfrom reaching the valves 206 and 208 and, in particular, the valve seats(e.g., the seat 236). It should be noted that the pressures in the domespaces (e.g., 224) of the regulators 202 and 204 do not have to be equal(i.e., the regulators may receive different pilot or control pressuresand, thus, different output pressures). Likewise, the fluid restrictors(e.g., 226) may be sized or configured similarly or differently toachieve desirable fill and/or bleed rates.

Further, it should be understood that while the example pressurereducing regulator 200 of FIG. 2 includes two pressure reducingregulators, alternative designs may include only one such regulator ormore than two regulators to suit a particular application. In onealternative example, an additional regulator may be bolted or otherwisefixed to the regulator 200. In that case, an additional inlet portconnects to the inlet of the added (e.g., third) regulator and theoutlet of the additional (e.g., third) regulator feeds pressure to thedomes (e.g., the dome space 224) of the regulators 202 and 204.Alternatively, the outlet of the added regulator may feed solenoids,which would serve to control the pressure in the domes (e.g., the domespace 224).

In addition to providing a highly stable output pressure, theconfiguration of the example regulator 200 eliminates the need forseveral fittings such as, for example, elbows, tees, etc. in comparisonto known multiple outlet pressure reducing regulators. In addition, theexample regulator 200 has a relatively smaller overall size and islighter weight in comparison to known multiple output regulators. Stillfurther, the example regulator 200 has relatively few internal partsand, thus, the cost of the example regulator 200 may be lower and thereliability may be higher than known multiple output regulators.

Although certain apparatus, methods, and articles of manufacture havebeen described herein, the scope of coverage of this patent is notlimited thereto. To the contrary, this patent covers all embodimentsfairly falling within the scope of the appended claims either literallyor under the doctrine of equivalents.

1. A pressure regulator, comprising: a body having a pressure inlet, acontrolled pressure outlet non-coaxially aligned with the pressureinlet, and a pressure control inlet; and a piston disposed in the bodyand having a first surface fluidly coupled to the pressure inlet, asecond surface fluidly coupled to the controlled pressure outlet, athird surface fluidly coupled to the pressure control inlet, and atransverse bore defining a fluid path through the piston and extendingbetween the first surface and the second surface to fluidly couple thepressure inlet to the controlled pressure outlet, wherein the firstsurface of the piston is configured to contact a valve seat and tocontrol the flow of fluid from the pressure inlet to the controlledpressure outlet in response to a difference between a pressure appliedto the third surface of the piston via the pressure control inlet and apressure applied to the first surface and the second surface of thepiston via the controlled pressure outlet.
 2. A pressure regulator asdefined in claim 1, wherein the piston comprises a central bore havingan annular surface configured to sealingly engage the valve seat.
 3. Apressure regulator as defined in claim 1 further comprising a spring tobias the piston into contact with the valve seat.
 4. A pressureregulator as defined in claim 3, wherein the spring engages a shoulderdefined by the second surface of the piston.
 5. A pressure regulator asdefined in claim 1, further comprising a plurality of sealing ringsengaged with the piston.
 6. A pressure regulator as defined in claim 5,wherein at least one of the sealing rings is an O-ring.
 7. A pressureregulator as defined in claim 1, wherein the valve seat is a plug-shapedmember.
 8. A pressure regulator as defined in claim 1, wherein the valveseat is made substantially of a plastic material.
 9. A pressureregulator as defined in claim 1, wherein the pressure inlet and the apressure control inlet are coaxially aligned.
 10. A pressure regulatoras defined in claim 1, further comprising a fluid restrictor seriallyinterposed in a fluid path fluidly coupling the pressure control inletto a chamber bounded by the body and the third surface of the piston.11. A pressure regulator as defined in claim 10, wherein the fluidrestrictor is removably interposed in the fluid path fluidly couplingthe pressure control inlet to the chamber.
 12. A pressure regulator asdefined in claim 1, wherein a chamber bounded by the body and the thirdsurface of the piston is devoid of any biasing member.